Optimisation of microwave-assisted extraction of pomegranate (Punica granatum L.) seed oil and evaluation of its physicochemical and bioactive properties

Abstract

Pomegranate seed oil was extracted in a closed-vessel high-pressure microwave system. The characteristics of the obtained oil, such as fatt y acid composition, free fatt y acidity, total phenolic content, antioxidant activity and colour, were compared to those of the oil obtained by cold solvent extraction. Response surface methodology was applied to optimise extraction conditions: power (176-300 W), time (5-20 min), particle size (d=0.125- 0.800 mm) and solvent to sample ratio (2:1, 6:1 and 10:1, by mass). The predicted highest extraction yield (35.19 %) was obtained using microwave power of 220 W, particle size in the range of d=0.125-0.450 mm and solvent-to-sample ratio of 10:1 (by mass) in 5 min extraction time. Microwave-assisted solvent extraction (MASE) resulted in higher extraction yield than that of Soxhlet (34.70 % in 8 h) or cold (17.50 % in 8 h) extraction. The dominant fatt y acid of pomegranate seed oil was punicic acid (86 %) irrespective of the extraction method. Oil obtained by MASE had bett er physicochemical properties, total phenolic content and antioxidant activity than the oil obtained by cold solvent extraction.